Originally Posted by footie
I understood that the MTM supercharged RS4 had it's CR reduced, was this not the case?
I think a good indicator of what is achievable as far as compression ratios and FI you should look at the Audi S6 and RS6 engine. In the S6 it's CR is 12.5:1 but with the RS6 it drops to 10.5:1, I would reckon much over this would cause problems long term and in any case you will have to lose that almighty rev range into the bargain.
I am still a little doubtful over the claimed improvements that have been achieved from such small alterations.
If you can't believe a longstanding BMW engineer (Karl-Otto Noelle) based in the same tiny Bavarian village as Alpina, who can you trust?